The need of controlling machine vibrations is recognized at the present time. The need for protection of atomic reactors from possible damage from earthquake vibration, an ever-present danger, is critical.
Metal springs occupy the unusual position that, in spite of the high modulus of elasticity of the material from which they are made, they act as admirable vibration isolators. The cantilever beam may be considered as a spring.
This invention consists of a structural element assembled from a three-dimensional cantilever beam with coupled flexural and torsional rigidity, and the combining into a cell of two or more of these elements. The cells shall be combined to take the place of helical compression and tension springs. The three-dimensional cantilever shall have an open section with top and bottom flanges parallel to the plan of the beam, the top and bottom flanges being connected with a web normal to the plan. The support end of the beam shall be hinged with a pin normal to the plan and passing through both top and bottom flanges and the support structure. See FIG. 1. The spring constant for this beam shall be varied by generating a bimoment in the flanges at the pinned end. These structural elements and cells can be economically made by any structural fabricator by welding together metal plates and structural members.
The following four tests were made in order to verify the functions of this structural element.